Rigid polymeric foam insulation laminates have been used in the construction industry for many years. For instance, they have been widely used as commercial roof insulation boards which are employed under asphaltic built-up roof (BUR) membranes as well as under various single ply membranes, such as EPDM rubber, polyvinyl chloride (PVC), modified bitumen membranes, thermoplastic polyolefins (TPO's), and the like. Other uses for such rigid polymeric foam insulation laminates include residential insulation, sheathing under siding, and roof insulation under asphalt shingles and concrete tiles.
Such insulation often takes the form of a core polymeric foamed thermoset material, such as a polyurethane, a polyisocyanurate, a polyurethane modified polyisocyanurate (often referred to as polyiso) or a phenolic resin, applied between two facing sheets.
Insulation boards are generally manufactured on production lines where a liquid core chemical mixture is poured over a bottom facer, foaming up to contact a top facer in a constrained rise laminator. The reaction of the chemical mixture causing foaming is generally exothermic, as curing via polymerization and crosslinking occurs in the laminator. In the case of polyisocyanurate insulation boards, the curing exotherm lasts well into the time the resulting rigid boards are cut, stacked and warehoused. The exotherm can continue for as long as 4 days and the mixture can reach temperatures as high as 325° F.
Desirable properties for the facers include flexibility, high tensile strength, high tear strength, and resistance to thermal degradation. Facer porosity should be low and the thickness of the facer coating should be sufficient to prevent bleed-through of liquid chemicals prior to foaming. Additionally, facers should exhibit good adhesion to the core foam insulation and be inert to the effects of extraneous chemicals which may be present in the mixture, especially blowing agents that also behave as solvents. Blowing agents currently in use include chlorofluorocarbons such as HCFC-141b and R-22 as well as hydrocarbons, such as n-pentane, cyclo-pentane and iso-pentane.
One problem that has plagued the polyiso industry has been a phenomenon called “cold temperature delamination”. This phenomenon occurs in cold temperature areas where insulation boards coming off the production line cool before they can be “stack cured”. In a worst case scenario, the polyiso core foam layer closest to the facer cools, quenching the cure reaction and leaving a brittle layer. This often leads to shearing of the core layer or facer peel off. It has been the practice of manufacturers to place a layer of corrugated cardboard over both the top facer surface of the top board and under the bottom facer surface of the bottom board in the stack, to retain exothermic heat and prevent subsequent delamination. Thus, a facer that inherently insulates and retains heat during stack cure would materially reduce incidents of cold temperature delamination and would eliminate the need for costly cardboard insulation.
After foamed polymer insulation boards are cured, cut and shipped to their use site, the facer should provide mechanical stability as well as water and weather resistance since, upon installation, they may be exposed to persistent rain, high humidity, ultraviolet light and excessive heat. Additionally, the facers must be puncture and scuff resistant to survive being fastened, e.g., by screws or nails, and walked on. Withstanding temperatures up to 500° F., as encountered in hot asphalt applications, as well as resistance to the deleterious effects of adhesive solvents used in single ply and cold applied roofing membrane applications while strongly bonding to the adhesives themselves are also important facer properties.
Traditionally, facer materials have included asphalt saturated cellulosic felts, fiberglass mats, asphalt emulsion coated fiberglass mats, aluminum foil/Kraft/foil, glass fiber modified cellulosic felts, glass mats onto which polymeric films have been extruded, and glass mats coated with polymeric latex/inorganic binder coatings. However, all of these materials have at least one undesirable property. For example, asphalt-containing products are not compatible with PVC single ply roofing membranes. Fiberglass mats are subject to excessive bleed-through of foamable core chemicals. Aluminum facers and foils reflect heat into the foam during processing which leads to disruption of cell structure, delamination and warping. Further, foil faced sheathing and extrusion or lamination of a polymer film to glass mat surfaces are costly. Specifically, glass mats coated with polymer latex/inorganic binder mixtures have been found to be brittle; conversely, glass fiber modified cellulosic felts are susceptible to moisture absorption aggravating board warping in damp or wet environments.
Other facers which have been employed for siding underlayment and insulation board facers include those disclosed in U.S. Pat. No. 5,776,841 and U.S. Pat. No. 5,717,012, which are primarily felts. U.S. Pat. No. 5,776,841 concerns a light weight sheet felt material suitable for use as roof and siding underlayment and insulation board facing which comprises on a dry basis (a) 60-80 weight percent cellulose fibers; (b) 15-30 weight percent glass fibers having a diameter of 5 to 16 microns and a length of ⅜-¾ inch; (c) 4-10 weight percent binder and (d) 0.5-10 weight percent non-asphaltic, sizing agent having a flash point above 150° F. and an evaporation rate less than one which is selected from the group consisting of anionic rosinous and amphipathic ester and anhydride sizes and mixtures thereof. The felt of U.S. Pat. No. 5,776,841 is of considerably lighter weight and higher porosity than other felting materials used for the same purpose and can be supplied in longer continuous sheet rolls than heretofore practical from a standpoint of handling, shipping, storage, and installation. Also the sheet felt of U.S. Pat. No. 5,776,841 can be produced on conventional felt making equipment in a one step process.
U.S. Pat. No. 5,001,005 describes a facing sheet composed of glass fibers and a non-asphaltic binder. The facer of U.S. Pat. No. 5,001,005 contains 60 percent to 90 percent glass fibers, which high fiber content does not provide sufficient binder to close the sheet's pores or to provide desired sheet strength. U.S. Pat. No. 5,102,728 describes a glass mat substrate coated with a polymeric latex blended with an asphalt emulsion, concerns a product which is not only incompatible with PVC roofing membranes but also requires excessive coating thicknesses to reduce high porosity. Accordingly, this product is very costly. U.S. Pat. No. 5,112,678 discloses a facer prepared by applying to a fiberglass mat a flowable polymer latex and an inorganic binder coating. The resulting product is somewhat brittle and is susceptible to an undesirable degree of chemical bleed through. U.S. Pat. No. 5,698,302 and U.S. Pat. No. 5,698,304 describe facers where polymer films are laminated or extruded onto fiberglass mat. Not only is this approach costly, but also since conventional mineral flame retardant filled polymers do not extrude well, some degree of resistance to flammability must be sacrificed.
U.S. Pat. No. 6,365,533, U.S. Pat. No. 6,368,991, and U.S. Pat. No. 6,774,071 describe a low fiber, plyable facer suitable for use in the construction industry, particularly for insulation board manufacture, comprising a dry preformed fiber mat containing a binder for the fibers, preferably a preformed glass mat, coated with a prefoamed composition which contains a polymer latex, a foam sustaining amount of a surfactant and a flame retarding and/or strengthening amount of a mineral filler and also to the use and process for the preparation of the above as well as to a siding underlayment or insulation board having a foamed, thermosetting resin core which is surfaced with said facer as a product for commercial use. These patents further describe a dry flexible facer comprising a non-asphaltic, non-cellulosic fiber mat surfaced with a cured foam comprising (a) between about 15 and about 80 weight percent of a polymer latex, (b) between about 0.01 and about 80 weight percent of a mineral filler and (c) between about 0.5 and about 10 weight percent of a foam supporting surfactant, and (d) between about 0.01 and about 5 weight percent of a catalyst.
Gypsum construction boards are widely used in building construction. Gypsum construction boards typically include a set gypsum core that is sandwiched between two facers. However, in some cases the gypsum core has a facer that is affixed to only one of its two sides.
United States Patent Application Publication 2005/0203205 discloses a composition of matter incorporating nanotechnology with UV curable materials for the coating of fiberglass. This patent publication more specifically discloses a one-part, substantially solvent-free coating composition for applying to fiberglass substrates, consisting essentially of: a polymerizable compound which comprises a mixture of acrylates, photoinitiator or a photoinitiator mix, silicon dioxide monospheres, and surfactant or mixture of surfactants. United States Patent Application Publication 2005/0203205 further reveals a composition of matter comprising UV curable materials incorporating nanotechnology for the coating of fiberglass This patent publication further discloses a one-part, substantially solvent-free coating composition for applying to a substrate, consisting essentially of: from about 60 percent to 80 percent by weight, based on total composition weight, of a polymerizable compound which comprises a mixture of acrylates, the acrylate mixture comprising an aliphatic urethane acrylate and a mixture of acrylate monomers, from 10 percent to 30 percent silicon dioxide monospheres of a diameter of approximately 20 nanometers, and from about 1 percent to 10 percent of an organic photoinitiator which initiates a polymerization reaction in the composition when it is exposed to ultraviolet light, without the use of added heat for either evaporation or postcure.